Millimeter-wave frequencies may be used to provide higher data rate communications for wireless networks, backhaul operations, and home entertainment applications, among others. PLLs that are utilized by receivers and transmitters operating at millimeter-wave frequencies are more difficult to design and implement because of the higher frequencies that need to be divided down to lower frequencies for phase comparison with a reference source. Some PLLs use ILFDs to initially divide down a high-frequency output of a voltage-controlled oscillator (VCO). One issue with conventional ILFDs is that the limited locking range makes them difficult to implement within millimeter-wave PLLs. Another issue with conventional ILFDs is that their power consumption makes them less desirable for use in mobile communication devices. ILFD locking range can be extended to some extent at the expense of higher power consumption.
Thus, there are general needs for millimeter-wave PLLs suitable for use in millimeter-wave communication devices. There are also general needs for ILFDs with a broader locking range. There are also general needs for ILFDs with lower power consumption suitable for use mobile communication devices.